1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * LED Heartbeat Trigger 4 * 5 * Copyright (C) 2006 Atsushi Nemoto <anemo@mba.ocn.ne.jp> 6 * 7 * Based on Richard Purdie's ledtrig-timer.c and some arch's 8 * CONFIG_HEARTBEAT code. 9 */ 10 11 #include <linux/module.h> 12 #include <linux/kernel.h> 13 #include <linux/init.h> 14 #include <linux/panic_notifier.h> 15 #include <linux/slab.h> 16 #include <linux/timer.h> 17 #include <linux/sched.h> 18 #include <linux/sched/loadavg.h> 19 #include <linux/leds.h> 20 #include <linux/reboot.h> 21 #include "../leds.h" 22 23 static int panic_heartbeats; 24 25 struct heartbeat_trig_data { 26 struct led_classdev *led_cdev; 27 unsigned int phase; 28 unsigned int period; 29 struct timer_list timer; 30 unsigned int invert; 31 }; 32 33 static void led_heartbeat_function(struct timer_list *t) 34 { 35 struct heartbeat_trig_data *heartbeat_data = 36 from_timer(heartbeat_data, t, timer); 37 struct led_classdev *led_cdev; 38 unsigned long brightness = LED_OFF; 39 unsigned long delay = 0; 40 41 led_cdev = heartbeat_data->led_cdev; 42 43 if (unlikely(panic_heartbeats)) { 44 led_set_brightness_nosleep(led_cdev, LED_OFF); 45 return; 46 } 47 48 if (test_and_clear_bit(LED_BLINK_BRIGHTNESS_CHANGE, &led_cdev->work_flags)) 49 led_cdev->blink_brightness = led_cdev->new_blink_brightness; 50 51 /* acts like an actual heart beat -- ie thump-thump-pause... */ 52 switch (heartbeat_data->phase) { 53 case 0: 54 /* 55 * The hyperbolic function below modifies the 56 * heartbeat period length in dependency of the 57 * current (1min) load. It goes through the points 58 * f(0)=1260, f(1)=860, f(5)=510, f(inf)->300. 59 */ 60 heartbeat_data->period = 300 + 61 (6720 << FSHIFT) / (5 * avenrun[0] + (7 << FSHIFT)); 62 heartbeat_data->period = 63 msecs_to_jiffies(heartbeat_data->period); 64 delay = msecs_to_jiffies(70); 65 heartbeat_data->phase++; 66 if (!heartbeat_data->invert) 67 brightness = led_cdev->blink_brightness; 68 break; 69 case 1: 70 delay = heartbeat_data->period / 4 - msecs_to_jiffies(70); 71 heartbeat_data->phase++; 72 if (heartbeat_data->invert) 73 brightness = led_cdev->blink_brightness; 74 break; 75 case 2: 76 delay = msecs_to_jiffies(70); 77 heartbeat_data->phase++; 78 if (!heartbeat_data->invert) 79 brightness = led_cdev->blink_brightness; 80 break; 81 default: 82 delay = heartbeat_data->period - heartbeat_data->period / 4 - 83 msecs_to_jiffies(70); 84 heartbeat_data->phase = 0; 85 if (heartbeat_data->invert) 86 brightness = led_cdev->blink_brightness; 87 break; 88 } 89 90 led_set_brightness_nosleep(led_cdev, brightness); 91 mod_timer(&heartbeat_data->timer, jiffies + delay); 92 } 93 94 static ssize_t led_invert_show(struct device *dev, 95 struct device_attribute *attr, char *buf) 96 { 97 struct heartbeat_trig_data *heartbeat_data = 98 led_trigger_get_drvdata(dev); 99 100 return sprintf(buf, "%u\n", heartbeat_data->invert); 101 } 102 103 static ssize_t led_invert_store(struct device *dev, 104 struct device_attribute *attr, const char *buf, size_t size) 105 { 106 struct heartbeat_trig_data *heartbeat_data = 107 led_trigger_get_drvdata(dev); 108 unsigned long state; 109 int ret; 110 111 ret = kstrtoul(buf, 0, &state); 112 if (ret) 113 return ret; 114 115 heartbeat_data->invert = !!state; 116 117 return size; 118 } 119 120 static DEVICE_ATTR(invert, 0644, led_invert_show, led_invert_store); 121 122 static struct attribute *heartbeat_trig_attrs[] = { 123 &dev_attr_invert.attr, 124 NULL 125 }; 126 ATTRIBUTE_GROUPS(heartbeat_trig); 127 128 static int heartbeat_trig_activate(struct led_classdev *led_cdev) 129 { 130 struct heartbeat_trig_data *heartbeat_data; 131 132 heartbeat_data = kzalloc(sizeof(*heartbeat_data), GFP_KERNEL); 133 if (!heartbeat_data) 134 return -ENOMEM; 135 136 led_set_trigger_data(led_cdev, heartbeat_data); 137 heartbeat_data->led_cdev = led_cdev; 138 139 timer_setup(&heartbeat_data->timer, led_heartbeat_function, 0); 140 heartbeat_data->phase = 0; 141 if (!led_cdev->blink_brightness) 142 led_cdev->blink_brightness = led_cdev->max_brightness; 143 led_heartbeat_function(&heartbeat_data->timer); 144 set_bit(LED_BLINK_SW, &led_cdev->work_flags); 145 146 return 0; 147 } 148 149 static void heartbeat_trig_deactivate(struct led_classdev *led_cdev) 150 { 151 struct heartbeat_trig_data *heartbeat_data = 152 led_get_trigger_data(led_cdev); 153 154 del_timer_sync(&heartbeat_data->timer); 155 kfree(heartbeat_data); 156 clear_bit(LED_BLINK_SW, &led_cdev->work_flags); 157 } 158 159 static struct led_trigger heartbeat_led_trigger = { 160 .name = "heartbeat", 161 .activate = heartbeat_trig_activate, 162 .deactivate = heartbeat_trig_deactivate, 163 .groups = heartbeat_trig_groups, 164 }; 165 166 static int heartbeat_reboot_notifier(struct notifier_block *nb, 167 unsigned long code, void *unused) 168 { 169 led_trigger_unregister(&heartbeat_led_trigger); 170 return NOTIFY_DONE; 171 } 172 173 static int heartbeat_panic_notifier(struct notifier_block *nb, 174 unsigned long code, void *unused) 175 { 176 panic_heartbeats = 1; 177 return NOTIFY_DONE; 178 } 179 180 static struct notifier_block heartbeat_reboot_nb = { 181 .notifier_call = heartbeat_reboot_notifier, 182 }; 183 184 static struct notifier_block heartbeat_panic_nb = { 185 .notifier_call = heartbeat_panic_notifier, 186 }; 187 188 static int __init heartbeat_trig_init(void) 189 { 190 int rc = led_trigger_register(&heartbeat_led_trigger); 191 192 if (!rc) { 193 atomic_notifier_chain_register(&panic_notifier_list, 194 &heartbeat_panic_nb); 195 register_reboot_notifier(&heartbeat_reboot_nb); 196 } 197 return rc; 198 } 199 200 static void __exit heartbeat_trig_exit(void) 201 { 202 unregister_reboot_notifier(&heartbeat_reboot_nb); 203 atomic_notifier_chain_unregister(&panic_notifier_list, 204 &heartbeat_panic_nb); 205 led_trigger_unregister(&heartbeat_led_trigger); 206 } 207 208 module_init(heartbeat_trig_init); 209 module_exit(heartbeat_trig_exit); 210 211 MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>"); 212 MODULE_DESCRIPTION("Heartbeat LED trigger"); 213 MODULE_LICENSE("GPL v2"); 214